No work was done on this project during 84-85 in favor of other projects. In view of the new project of hot tip catheter methods for disintegration of atherosclerotic plaque some additional experiments were done to compare microexplosives, hot tips and laser effects on atherosclerotic plaque. The 83-84 work established that silver azide explosive charges that produce energy equivalent to that delivered by lasers could be detonated at the end of an intravascular catheter and positioned to direct the energy to the target plaque. In addition it was shown that the azide charge could be shaped to concentrate the energy to a specific localized point equivalent to that produced by laser beams. It was further noted that the use of exploding oxyhydrogen gas in the catheter to initiate the azide detonation produced a partial vacuum following the explosion that aspirated the debris of the explosion into the catheter. The additional work done this year perfected the production of "shape charges" by pressing the silver azide in a hard steel die against a .062" steel ball. The focused discharges were tested against artherosclerotic plaque in human post mortum aortic specimens and the lesions produced were examined histologically and compared to those produced by the hot tip catheter or laser shots by various types. The principle drawback of the method remains the inability to repeat the shots without reloading the azide on the catheter tip.